Tribological Properties Of Composites Research Articles

Surface modification of polytetrafluoroethylene (PTFE) fibers through methyl methacrylate (MMA) polymerization for self-lubricating composites

PTFE fibers exhibit strong inertia and possess restricted interfacial compatibility with resin, thereby constraining the application of PTFE self-lubricating composites. To address this issue, PTFE-g-MMA fibers were synthesized by grafting MMA onto the surface of PTFE fibers using high-energy irradiation and chemical grafting techniques, resulting in the enhancement of the tribological properties (the friction coefficient has been reduced by approximately 42.2% and the wear rate has been reduced by about 87.9%) and mechanical properties (the interlaminar shear strength (ILSS) experienced a substantial increase of approximately 45.8%) of the composites. The influence of grafting modification on the formation of PTFE transfer films and the effect of modification time on the tribological properties of composites were investigated systematically. The results indicated that graft modification disrupted the C–F bond of PTFE and promoted the formation of metal-chelated carboxylates, facilitating the formation of PTFE transfer films on the counter surface. This research could provide a general and feasible strategy for large-scale modification of PTFE fibers with exceptional comprehensive properties.

Effect of strontium sulfate on microstructure and high-temperature tribological properties of Co matrix composites

To enhance the resistance to wear of Co matrix alloy as high-temperature hot-end parts, the Co-based composites reinforced by strontium sulfate (4.0, 9.0 and 14.0 wt%) were prepared by using a powder metallurgy technology (P/M). The effects of SrSO4 on the microstructure, phase and tribological properties of composites were systematically investigated. The tribological behaviors of Co-based composites were tested from room temperature to 800 °C against Si3N4 ball by a ball-on-disk tribo-tester. The results indicated that SrSO4 decomposed during sintering, and the tribological properties of composites were improved by the addition of SrSO4. The composite with 9.0 wt% SrSO4 had favorable tribological behavior, which was attributed to the in-situ synthesized solid lubricants and lubricating film formed on the contact surfaces.

Experimental investigation on triglycidyl isocyanurate‐based tribologically functional composites

AbstractThe aim of this study is to prepare epoxy/polytetrafluoroethylene (PTFE)/glass fiber (GF) composites (EPGs) with the unique characteristics of low friction and high wear resistance based on triglycidyl isocyanurate (TGIC). The tribological properties of composites with different filler ratios under different working conditions were systematically studied. At the maximum filler content of 40 wt% PTFE, the minimum coefficient of friction (COF) and wear rate reached 0.079 and 0.45 × 10−6 mm3/N·m. The hardness decreased by 44.2% and the density increased by 18.3%. The worn surfaces and transfer films were observed and analyzed by scanning electron microscopy (SEM) and x‐ray photoelectron spectroscopy (XPS). The increasing tendency of velocity and amplitude is beneficial to reduce the carbon‐rich region and further enhance the formation of transfer films. It is proved that the tribological properties of TGIC‐based epoxy composites are higher than those of other types of epoxy composites. This study offers great insight into the tribological applications of TGIC‐based epoxy composites.Highlights Epoxy/PTFE/GF composites (EPGs) were prepared using TGIC as the base material. EPGs have good mechanical and tribological properties. The COF of EPG3 reaches 0.079 and the wear rate becomes 0.45 × 10−6 mm3/(N·m). The increasing tendency of velocity and amplitude is beneficial to reduce the carbon‐rich region and further enhance the formation of transfer films.

Synergistic optimization of mechanical and tribological properties of TiC modified copper-graphite composites by direct current in-situ sintering

The application of Cu-graphite composites in the field of friction materials is limited by the poor wettability between Cu and graphite and weakened mechanical properties. In this work, in-situ TiC layers were generated by interfacial resistance sintering with direct current to manipulate the interfacial bonding of the composites and enhance their comprehensive properties. The Ti added to the composites would react with graphite at the interface to generate TiC layers and form strong Cu–TiC-graphite interfaces due to interfacial reactions. When the added Ti content is 6 wt%, the composite demonstrates the most excellent mechanical properties and tribological characteristics, i.e., yield strength (168 MPa) and wear rate (2.7 × 10−10 m2/N) are 93.1% higher and 29.7% lower than those of the Cu-graphite composite without Ti addition, respectively. The dense TiC layer induces the strengthening of the Cu matrix and serves as the reinforcing phase to optimize the interfacial bonding and stress transfer, which not only greatly enhances the mechanical properties of the composite but also enables the composite to take full advantage of the hard TiC and graphite phases to obtain stable friction coefficient and low wear rate. This work provides a simpler technique to prepare modified Cu-graphite composites with excellent performance and contributes to the in-depth understanding of the enhancement mechanism of hard ceramic layers on the mechanical and tribological properties of composites.

Influence of Metallic Particles on Properties of Aluminium Composites through Taguchi Technique

In this work, aluminium composites have been evaluated in terms of their characteristics and behaviour. Stirring metallics and a specific quantity of ceramic-derived silicon nitride resulted in AA6061 composites (Si3N4). The mechanical, corrosion, and tribological properties of composites were investigated. Tensile, corrosion, and hardness characteristics have been improved in composites with a constant weight percent of ceramic and advanced metallic fortification. The improved hardness of the composite has decreased wear and friction. Furthermore, by using ceramic strengthening with the metal, the impact strength of the composites was condensed. In addition to the research, the design of experiments method was used to optimize the important wear test elements such as reinforcement %, applied stress, sliding distance, and speed. Analysis of variance was used to find the most significant testing features and its interface with wear performance and the friction coefficient of the composite specimen.

Developing PMMA/Coffee Husk Green Composites to Meet the Individual Requirements of People with Disabilities: Hip Spacer Case Study

When replacing a damaged artificial hip joint, treatment involves using antibiotic-laced bone cement as a spacer. One of the most popular materials used for spacers is PMMA; however, it has limitations in terms of mechanical and tribological properties. To overcome such limitations, the current paper proposes utilizing a natural filler, coffee husk, as a reinforcement for PMMA. The coffee husk filler was first prepared using the ball-milling technique. PMMA composites with varying weight fractions of coffee husk (0, 2, 4, 6, and 8 wt.%) were prepared. The hardness was measured to estimate the mechanical properties of the produced composites, and the compression test was utilized to estimate the Young modulus and compressive yield strength. Furthermore, the tribological properties of the composites were evaluated by measuring the friction coefficient and wear by rubbing the composite samples against stainless steel and cow bone counterparts under different normal loads. The wear mechanisms were identified via scanning electron microscopy. Finally, a finite element model for the hip joint was built to investigate the load-carrying capacity of the composites under human loading conditions. The results show that incorporating coffee husk particles can enhance both the mechanical and tribological properties of the PMMA composites. The finite element results are consistent with the experimental findings, indicating the potential of the coffee husk as a promising filler material for enhancing the performance of PMMA-based biomaterials.

Mechanical and tribological characterization of graphene nanoplatelets/Al2O3 reinforced epoxy hybrid composites

This study aimed to determine the effects of varying Aluminum oxide (Al2O3) and Graphene Nanoplatelets (GNP) concentrations on epoxy-based polymer composites’ mechanical and tribological characteristics. Al2O3 (1 to 5 wt.%) and GNP (0 to 1 wt.%) reinforced epoxy matrix composites were produced with sonication and stirring magnetic route. Mechanical, microstructural and tribological properties of composites were investigated via X-ray diffraction (XRD), Archimedes’ Method, Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDX), Raman spectroscopy, hardness, impact, tensile, compressive and wear tests. The highest ultimate tensile strength and compressive strength were found at 62.83 and 137 MPa for 3 wt.% reinforced Al2O3 epoxy matrix composites, and it was observed that there was a 38% and 17% increase compared to neat epoxy, respectively. The highest impact strength was found for 3 wt.% Al2O3 and 1 wt.% GNP-reinforced composites and increased by 19% compared to neat epoxy. The best hardness was found for 3 wt.% reinforced Al2O3 and 0.25 wt.% GNP-reinforced composite, and there was a 22% increase in hardness compared to neat epoxy. Also, the highest wear resistance (1.686x10−6 mm3/Nm) and lowest Coefficient of Friction (COF, 0.13755) were determined for the same specimen.

The Influence of Mullite Shape and Amount on the Tribological Properties of Non-Asbestos Brake Friction Composites

For investigating the effect of mullite as a reinforced fiber of the non-asbestos brake friction material on the performance of brake pads, mullite reinforced composites with different contents (5% and 10%) and shapes (powder-based and fiber-based) were developed, and the physical and mechanical properties of the composites were analyzed. The tribological properties of the composites were tested by a Chase tester followed by the IS-2742 standard, and the worn surface was investigated by three-dimensional surface topography and SEM. The results show that the brake friction material with 5% powdered mullite performs best, having the highest stable friction performance (0.86), the lowest wear rate (3%), the lowest friction variation performance (0.263), and the best fade-recovery performance. With the increase of mullite content, the friction variation, wear resistance, and friction stability of the composites become worse. Meanwhile, the performance of powder-based mullite composites is better than that of fiber-based. The worn surface analysis shows that the fiber-based mullite composite has a higher surface roughness, fewer contact platforms, more wear debris, and peeling pits. In contrast, the powder-based mullite composites have a better surface performance. It provides a practical basis for mullite-reinforced non-asbestos brake friction materials.

Effects of in-situ formed Ag2Al on tribological properties of nominal MoAlB-Ag composites at high temperatures

The MoAlB-Ag composites with different amounts of Ag were prepared through in-situ formed Ag2Al method, and the tribological properties of the composites were systematically studied from RT to 800 °C. The in-situ formed Ag2Al plays an important role in tribological behavior. Below 600 °C, due to the decomposition of Ag2Al, Ag lubricating film is formed on the worn surface, leading to a lower friction coefficient of 0.31 and wear rate of 8.24 × 10-6 mm3·N-1·m-1. Above 600 °C, Ag2Al is transformed into Ag and Al2O3, and Al2O3 will aggravate wear via abrasive wear. While at 800 °C, when the Ag content is lower than 20 wt%, the wear mechanism turns into the collaborative lubrication of Ag and MoO3 because of the oxidation of the matrix.

Role of carbonaceous reinforcements on mechanical properties and micro-scratch behaviour of Y2O3 stabilized ZrO2

An efficient 3 mol% Y2O3 stabilized ZrO2 (3YSZ) based composite was developed for structural application. The role of graphene nanoplatelets (GNP) and multi-walled carbon nanotubes (MWNT) on evolution of phases and microstructural features in the 3YSZ-based composites that affect the mechanical and tribological properties of composites have been investigated in the present study. Here, the spark plasma sintered 3YSZ composites with 1, 2 and 4 wt% of MWNT and GNP reinforcement were synthesised. Sintered composites retained the tetragonal ZrO2 (t-ZrO2, high-temperature phase) along with the formation of ZrC with the addition of GNP/MWNT, which marginally improves the mechanical properties of the composite. The marginal enhancement in hardness and elastic modulus with GNP and MWNT reinforcement is attributed to the synergistic effect of grain refinement, densification, phases and distribution. The composite with 2 wt% of MWNT showed marginal improvement in the indentation fracture toughness (7.2 MPa m0.5) compared with monolithic 3YSZ by crack deflection, MWNT bridging & pull-out mechanism. Further, the average scratch toughness of the 3YSZ-GNP/MWNT based composite is measured as 1.99–2.15 MPa m0.5 derived from progressive load scratching. The scratch toughness with 1.5–3.3 times lower than the indentation fracture toughness is attributed to the elastic recovery during scratching and non-uniform distribution of phases in the composites. Further, the optimum value of hardness, elastic modulus, indentation fracture toughness, and scratch toughness of 2 wt% of MWNT reinforced 3YSZ composite is found suitable for structural applications.

Mechanical and tribological properties of WC particles reinforced Cu-20Zn matrix composites

Tungsten carbide (WC) particles can be used as reinforcement to improve the mechanical and tribological properties of metal matrix. Herein, WC reinforced Cu-20Zn matrix composites were prepared. The mechanical and tribological properties of composites were also investigated. It was confirmed that the Cu3Zn solid solution was formed during the sintering process. Due to the solid solution and load transfer strengthening mechanism, the tensile and flexural strength were significantly improved. When the WC content was 30 wt%, the tensile and flexural strength were both increased by about two times compared with Cu-20Zn alloy. Additionally, the two-body abrasive and adhesive wear were gradually weakened with increasing WC content. When the WC content was 30 wt%, the composites showed low friction coefficient and wear rate. The formation of tribo-film, which was induced by tribo-oxidation reaction, was conceived to be responsible for the favorable lubricating properties.

The Role of Artificial Neural Networks in Prediction of Mechanical and Tribological Properties of Composites—A Comprehensive Review

The Role of Artificial Neural Networks in Prediction of Mechanical and Tribological Properties of Composites—A Comprehensive Review

Tribological properties of organotin compound modified UHMWPE

Abstract A range of ultra-high molecular weight polyethylene (UHMWPE)/tetraphenyltin (Ph4Sn) nanocomposites were fabricated by hot-pressing. The surface hardness and crystallinity of composites were studied. It revealed that the surface hardness of the composites decreased slightly, and the changing trend of crystallinity was consistent with the hardness. The tribological properties of composites under seawater lubricating conditions were investigated. The experimental results showed that the friction coefficients of the composites almost keep the same but the wear reduced sharply. With the increases of Ph4Sn content, the wear of composites first decreases significantly and then increases, meanwhile the friction coefficient remains basically unchanged. The dominant wear mechanism has changed from adhesive wear to plastic deformation and finally to abrasive wear. The addition of Ph4Sn particles reduces the sensitivity of the Ph4Sn/UHMWPE composites to water and transfers the load to the UHMWPE network, resulting in the wear resistance improved.

Influence of the particle size on the physical, mechanical and tribological properties of composites for brake pads

Tribotechnical indicators of environmentally friendly frictional composite materials with phenol-formaldehyde matrix are studied. Friction tests were carried out on a MMW-1 vertical tribometer according to the pin-on-disk scheme. Keywords: brake pads, composites, friction and wear, plasticizers, degradation, porosity. fikratyusub@gmail.com

Preparation and tribological behavior of polytetrafluoroethylene/metal mesh composites with sandwich structure

AbstractPolytetrafluoroethylene (PTFE) owns an excellent self‐lubricating performance, but its wear rate is very high due to the large‐scale spalling of the matrix in the friction. In this paper, A new kind of PTFE composites with sandwich structure was prepared by layer‐press technology, whose middle layer is filled with metal mesh. The influence of the mesh structure and mesh density of middle metal layer on tribological properties of composites were researched in detail. The results revealled that the metal mesh located in the composites can efficiently prevent the large‐scale spalling of PTFE, which induces the sample of PTFE/500# plain woven dutch metal mesh (PTFE‐500#PWD) to have a lower wear rate (9 × 10−5 mm3/Nm) and COF (0.106) under the fixed experimental condition. The prepared PTFE/metal mesh composites reveal excellent anti‐friction and anti‐wear performance, which can be used to fabricate a new kind of self‐lubricating materials.

Influence of pyrolytic carbon interphase and pyrolysis temperature on the mechanical and tribological properties of Cf/SiC after heat treatment at 1800 °C

The influence of pyrolytic carbon (PyC) interphase and different pyrolysis temperatures on the mechanical and tribological properties of Cf/SiC fabricated via polymer infiltration and pyrolysis after heat treatment at 1800 °C was investigated in this study. It was shown that the PyC interphase and high pyrolysis temperature were beneficial for protecting the carbon fibres and reducing the oxygen content in the matrix. Composites with PyC interphase and high pyrolysis temperature exhibited high flexural strength and fracture toughness after heat treatment. In addition, the results of reciprocating sliding tests showed that the tribological properties of composites with PyC interphase and high pyrolysis temperature were improved, and the high-strength fibres in the composite were beneficial to the formation and stabilisation of friction film at high frequencies.

Influence of mixing process on the mechanical and tribological properties of PTFE composites

ABSTRACT Polytetrafluoroethylene (PTFE) composites filled with glass fibre (GF) and graphite were prepared by internal mixer and moulded using compression mould to produce test samples. A high-speed mixer was selected to simulate uneven mixing and excessive mixing conditions by controlling different mixing time. The work studied the mixing process's influence on the mechanical and tribological properties of PTFE composites and investigated the state of glass fibres on the unworn/ worn composite surface with SEM characterisation. The results revealed that the mechanical and tribological properties of composites were associated with the mixing process. For the non-uniform mixing of composite materials, glass-fibre particles fell off the matrix earlier, hindering glass fibre particles in bearing the matrix load. Moreover, excessive mixing increased mixing temperature, the matrix material softened due to overheating, which caused the adhesive wear between the steel ring and PTFE composites. It increased the volume wear rate of composite materials.

Comparative Study on Tribological Behavior of Graphene/Polyimide and Carbon Fibers/Polyimide Composites: A Review

Recently, graphene and carbon fibers have enticed extensive consideration in many scientific fields, they are considered by many scientists to be one of the most promising materials in the 21st century. Due to the uniqueness of their properties was attracted to be used to reinforce polyimide. Impressive graphene properties coupled with those excellent of polyimide composites produced composites materials with good tribological properties, different contents of graphene and its derivatives tend to improve polyimide composites properties particularly friction and wear. Furthermore, nanofillers decorated graphene derivatives showed also an effect on the tribological properties of composites. Carbon fibers coupled with polyimide composites also reviewed and showed a significance in the improvement of the properties of composites materials. The results nanofillers reinforced carbon fibers/polyimide exhibit enhanced tribological properties, which can be applied in various fields. Therefore, this survey article gives an enormous review study of the tribological properties under various conditions of graphene/polyimide and car- bon fibers/polyimide composites. Besides the effects of nanofillers size on tribological properties, preparation, and research challenges were also reviewed.

On the Microstructure, Strength, Fracture, and Tribological Properties of Iron-Based MMCs with Addition of Mixed Carbide Nanoparticulates.

In this paper, the features of the strength, fractures, and tribological behavior of metal-matrix composites based on the FeGr1 material are discussed. To improve the material properties, a mixture of SiC, Al2O3 and C nanoparticulates have been added to an iron-based matrix. The simplex lattice design method and hardness, compression, and bending tests were used to determine the mechanical properties. Scanning electron microscopy was applied for fracture features analysis. Different fracture types, mainly trans-crystalline quasi-brittle and brittle fracture or inter-granular fracture and microcracks were registered for the composites tested. Depending on the type and amount of ceramic additives, significant changes in strength, as well as in the fracture features of the metal-matrix composites (MMCs), were observed. Based on tribological tests, changes in the momentary coefficients of friction, temperature of the friction surface, and wear rate of the composites with nanoparticulates were described. An analysis of the worn surface morphology revealed changes in the wear process depending on the MMC composition. It was shown that the use of hybrid mixed additives based on hard ceramic nanoparticulates improved both strength and tribological properties of composites.

The effects of β-Si3N4 whiskers and Fe–Cr–C alloy on the tribological properties of bronze matrix composites

In order to improve the wear resistance, Fe–Cr–C alloy and β-Si3N4 whiskers were chosen as the hard phases in bronze-graphite to prepare self-lubricating composite. Friction behaviors were tested with counter material 45# steel to evaluate the tribological properties of composites. The results indicated that Fe–Cr–C alloy and β-Si3N4 whiskers played different roles in composites. β-Si3N4 whiskers can obviously decrease the wear rate by excellent wear resistance. While the Fe–Cr–C alloy had better wettability with matrix, which improved the interfacial bonding and provided a continuous wear resistance. Moreover, Fe–Cr–C alloy also played a role in maintaining the friction coefficient stability, and this effect was more significant in the conditions of high rotational speeds. The composite containing 12.5 vol.% β-Si3N4 whiskers and 2.5 vol.% Fe–Cr–C alloy in this research showed good friction performance.